Manually-extracted unfertilized eggs of Chinese oak silkworm, Antheraea pernyi, enhance mass production of Trichogramma parasitoids

Antheraea pernyi Guerin-Meneville eggs have become an important host for rearing Trichogramma and are the preferred host for mass production of Trichogramma dendrolimi Mausumura, a widely used natural enemy in pest control practices. However, the effects of fertilization of host eggs on their mass production remains unclear. In this study, we evaluated parasitism and biological parameters for T. dendrolimi reared on A. pernyi eggs with five different treatments under the laboratory conditions. The five treatments were manually-extracted unfertilized washed eggs (MUW), naturallylaid unfertilized washed eggs (NUW) and unwashed (NUUW) eggs, naturally-laid fertilized washed eggs (NFW) and unwashed (NFUW) eggs. Our results showed that T. dendrolimi preferred MUW eggs to other treatments, although all treated A. pernyi eggs were accepted by T. dendrolimi. Generally, T. dendrolimi parasitized more washed eggs than unwashed eggs, and a greater number of unfertilized than fertilized eggs. On MUW eggs, the highest number of adults emerged per egg coupled with the shortest pre-emergence time and longest longevity of offspring. Those T. dendrolimi adults emerging from unfertilized eggs exhibited a higher number per egg, shorter pre-emergence time and longer adult longevity than those from fertilized eggs. There was no significant difference in percentage of female progeny, time to adult death, hind tibia length and egg load across all treatments. Our results demonstrate that MUW eggs of A. pernyi are most suitable for mass production of T. dendrolimi.